The present invention relates to a tracked vehicle drive/steering system.
Known production tracked vehicles, such as the John Deere 8000T and 9000T series track tractors have a hydrostatic steering system which includes an engine-driven variable displacement steering pump which powers a hydraulic fixed displacement steering motor. The steering motor drives, via a cross shaft and a gear a left planetary drive. The steering motor also drives, via the cross shaft, a gear and a reverser gear, a right planetary drive. A steering control signal is provided by a transducer which detects rotation of a steering wheel. A pump displacement control controls the output of the pump as a function of the steering control signals. The speed and direction of rotation of the steering motor is normally proportional to the position of the steering wheel, and these parameters are sensed by a Hall effect motor speed and direction sensor. The output of the steering system is motor speed, which is measured using a Hall effect motor speed and direction sensor. It would be desirable to have a means of detecting and responding to pump malfunctions wherein the pump output flow exceeds the amount which corresponds to the steering control signal and that which is commanded by the pump displacement control.